Car appreciation... the aesthetics, the engineering, etc

At the risk of outing myself as 'not much of a driver' (passed test 3 years ago at 31, after about 5 hours of lessons having never driven before and the urgency of a new baby spurring me on - since then done about 15000 miles a year in my wife's 2008 kia ceed, which I recently killed) what's the difference between petrol and diesel?

My understanding is:

diesel is (currently) more expensive, but can be more economical to run?
it provides or is associated with more torque for quicker bursts of power when needed
it emits less CO2 (but has other emissions associated with lung problems like asthma)
diesel cars tend to cost more to buy and more to get serviced/repaired
depending on model may be unable to go into certain ULEZs - which could be an issue for me.

it'll be largely a work expense so if there are costs, there are costs. That said if a diesel is black hole, maybe I should avoid it.

I feel (the non driver in me) that I'd rather get a new fully electric van (was looking at a Nissan e-nv200 combi) but I don't have 30 grand sitting around and don't want to get sucked into credit (even a couple of hundred quid a month) when I'm self employed / the sole earner in house and in a relatively precarious line of work which covid hasn't helped and brexit won't either.

When I do get paid, I do get paid, so I could cobble together between 5 and 10 grand in cash for a car without too much stomach churning (lower half of that figure would be nicer). I usually carry 200-300kg of kit to a job, sometimes double that. I live in Devon and usually drive to jobs in London, Milton Keynes and Southampton. The kit is typically heavy, flat and boxy but with some long things (so the 2.8m internal space the Berlingo offers sounds great).

I remember seeing this:

get turned into this:

which is frankly the dream - but I'd still need to fit a child seat in there somewhere because I'm not having two vehicles. Have contemplated ratchet strapping him to the roof but was vetoed.